1. Field of the Invention
The present invention relates to a cable with a spliced section covered in a protective material. More specifically, the present invention relates to a data cable configured for use in high pressure underwater environments in which a splice is made in the cable, and an overmold is formed over the splice to form a water-tight seal.
2. Discussion of Background Information
Wires and cables are used to carry data from one point to another. Referring now to FIGS. 1A and 1B, a wire 100 is typically made from an inner conductor 102 such as uniform or wound strands of copper, with an over molded insulating layer 104. Several wires 100 are typically wound together (e.g., twisted pair), and then covered by an outer jacket 106 (often referred to as a “belt”) to form a cable 108. Outer jacket 106 and insulating layer 104 are typically removed at the ends of these cables 108 so that the conductors 102 can be exposed and connected to other electronic elements.
The nature of the number and arrangement of wires 100 restricts the selection of materials that can be used for the insulating layer 104. For example, for a single wire 100 as shown in FIG. 1A, which lacks an outer jacket 106, insulating layer 104 could be made of polyethylene. However, when multiple wires 100 are used to form the cable 108, polyethylene cannot be used because it would melt during application of the outer jacket 106; the individual wires 100 would become a multi-wire suspension within a solid mass, making it impossible to splice the wires at the end. For these reasons, insulating layer 104 is typically made from a Teflon-based material.
Often cables such as shown in FIG. 1B need to be spliced and placed in high pressure underwater environments. Typical efforts involve the application of some type of material(s) around the exposed cables to form a seal, such as polyethylene. However, the Teflon in insulating layer 104 has poor bonding qualities, and therefore will not form a strong bond with the applied sealants. Under extreme pressure, the water will break the seal, reach the underlying exposed wires, and flow back up the wire pathways to upstream and downstream elements.
Cross-linked polyethylene has been used as an outer insulating layer in high voltage power cables due to its high dielectric constant and resistance to stress cracking. Such high voltage power cable wires are usually encased in an outer jacket made of rubber.